Re: Oxygen level in Mezoic

["David Marjanovic" <david.marjanovic@gmx.at>]

> Maybe big dragonflies were extinctified by
> competition from/predation by pterosaurs or dino-birds; any idea as to the
> timing of the appearance and disappearance of these groups?

Yes... big dragonflies didn't live to see the Triassic, it seems (I suspect
the P-Tr mass extinction). Ptero- and dinosaurs probably appeared quite some
time later, as their oldest fossils are LTr and their closest relatives MTr.

There once was a short article in New Scientist (maybe I can find it) on
atmospheric oxygen through time. Says 35 % in the Carboniferous and Permian,
then around the normal 21 % until the mid-Jurassic, then 26 % until the
Eocene, then 21 again. I recall amber being mentioned... is there any
Carboniferous amber? In any case everything is tentative. :-)